public class Card {private String card_number;
    private String password;
    public Card(String card_number, String password) {
        super();
        this.card_number = card_number;
        this.password = password;
    }
    public Card()
    {
        this.password = "123321";
    }

    public static void main(String[] args) {
        Card c1=new Card();
        System.out.print("卡号"+c1.card_number);
        System.out.println("密码"+c1.password);
        Card c2=new Card("454646","sauwew");
        System.out.print("卡号"+c2.card_number);
        System.out.println("密码"+c2.password);
    }
}
